Breast tissue is composed of glandular tissues specialized for lactation, and a connective tissue stroma containing blood vessels, adipose tissue, nerves, and lymphatic tissue. Breast tissue is bounded by the skin. About 90% of all breast cancers originate in the lactiferous ductal tissue of the breast, with the remaining 10% beginning in the glandular tissue lobules.
Recent estimates indicate that breast cancer will develop in about twelve percent of women in the United States during their lifetimes. The risk of developing breast cancer increases with the age of a woman. In addition, inherited and environmental factors can increase the risk for breast cancer. One way a woman can minimize her risk for developing breast cancer is to have one or both breasts removed by a prophylactic mastectomy. This method is disadvantageous because of its attendant discomfort and disfigurement.